1. Field of the Invention
The present invention relates to an apparatus and method for determining the type of an optical disk in order to implement an optimal servo operation according to the type of a loaded optical disk.
2. Description of the Related Art
FIG. 1 is a flowchart showing an example of a method for determining the type of an optical disc employed in a conventional optical disk device. The conventional method for determining the type of an optical disk will now be described with reference to FIG. 1.
In the prior art, when an optical disk is loaded, it is determined, from an FG signal detected as a spindle motor rotates, whether the optical disk is loaded and whether the loaded disk is 8 or 12 cm in size, and it is also determined whether it is a CD-RW (S1). This determination may be based on the reflectivity of the optical disk, i.e., the level of a focusing error signal detected when an objective lens is moving in a direction perpendicular to the disk surface while an internal laser diode LD in an optical pickup is turned on.
After such disk discrimination has been performed, the optical disk device turns a focusing servo on after adjusting the focusing gain and the offset of an R/F IC according to the disk discrimination result (S2). Then, the optical disk device turns a tracking servo on after adjusting the tracking gain (S3).
Next, the optical disk device shifts to a recording mode and performs a corresponding adjustment operation, and also performs an automatic focusing/tracking gain adjustment operation of both a digital recording signal processor and a digital reproduction signal processor, and a gain adjustment operation of the R/F unit (S4 and S5).
If it is determined that the loaded optical disk is not a CD-RW (S6), the optical disk device turns a wobble servo on for reading ATIP (Absolute Time In Pre-groove) signals after the focusing and tracking gain adjustment operation and the recording mode adjustment operation have been performed, and checks whether an ATIP signal is detected within a predetermined time, so as to determine whether the optical disk is a CD-R or CD-ROM (S7). If an ATIP signal is detected within the predetermined time, the optical disk device determines the optical disk to be a CD-R (S8). On the contrary, if no ATIP signal is detected within the predetermined time, the optical disk device determines the optical disk to be a CD-ROM (S9). When such disk discrimination has been completed, the optical disk device performs a requested operation (S10).
In the prior art, as described above, the determination as to whether the loaded optical disk is a CD-R or CD-ROM is performed after the focusing and tracking servo adjustment has been completed.
However, the conventional optical disk device (for example, a CD-RW drive) generally employs the same tracking servo scheme, i.e., a push-pull tracking servo scheme having a high optical efficiency, irrespective of the type of a loaded optical disk, although it is required to employ an optimal tracking servo scheme according to the type of the optical disk in order to improve the reproduction characteristics. The conventional device thus has a problem in that the reproduction and/or recording characteristics are degraded for CD-R and CD-ROM disks.
In addition, the conventional device performs the recording mode adjustment operation and the automatic focusing/tracking gain adjustment operation of the digital recording signal processor, as described above, before determining whether the optical disk is a CD-R or CD-ROM. For this reason, if the loaded optical disk is a CD-ROM, i.e., a read-only disk, the reproduction operation is delayed since the unnecessary adjustment operation is performed.